logs: use %o to format error

otherwise, they are printed as multi-line and this messes up tail+date formatting

src/users.js

@@ -395,7 +395,7 @@ async function verifyWithUsername(username, password, identifier, options) {
     const [error, newUserId] = await safe(externalLdap.maybeCreateUser(username.toLowerCase()));
     if (error && error.reason === BoxError.BAD_STATE) throw new BoxError(BoxError.NOT_FOUND, 'User not found'); // no external ldap or no auto create
     if (error) {
-        debug(`verifyWithUsername: failed to auto create user ${username}`, error);
+        debug(`verifyWithUsername: failed to auto create user ${username}. %o`, error);
         throw new BoxError(BoxError.NOT_FOUND, 'User not found');
     }